Optical Wavelength Division Node

1. An optical wavelength division node connected with and provided between an optical line terminal (OLT) and a plurality of optical network unit (ONU), comprising: an optical splitter for receiving a downstream signal light source with a single wavelength transmitted by the OLT and splitting the received downstream signal light source into a first-path signal light source and a second-path signal light source; a plurality of optical circulators sequentially and individually connected to each of the plurality of ONUs, wherein the optical circulator in a first-order position receives the first-path signal light source transmitted by the optical splitter and transmits the first-path signal light source received from the optical splitter to the ONU in a first-order position, so as to receive a return signal transmitted by the ONU in the first-order position and then pass the return signal received from the ONU in the first-order position to the optical circulator in a second-order position, until the optical circulator in a last-order position receives the return signal transmitted by the ONU in a last-order position and transmits the return signal received from the ONU in the last-order position; and a colorless light source module for receiving the second-path signal light source transmitted by the optical splitter and the return signal transmitted by the optical circulator in the last-order position, and using the second-path signal light source to modulate the return signal received from the optical circulator in the last-order position to generate an upstream signal light source to be then transmitted back to the OLT by the optical splitter; wherein the colorless light source module comprises at least two colorless light source transceivers, a first switch and a second switch; wherein the first switch is connected with the two colorless light source transceivers and the optical circulator in the last-order position; and wherein the second switch is connected with the two colorless light source transceivers and the optical splitter.

2. The optical wavelength division node of claim 1 , wherein the optical splitter is a 1-to-2 optical splitter.

3. The optical wavelength division node of claim 1 , wherein each colorless light source transceiver includes two semiconductor optical amplifiers, a first optical circulator, a second optical circulator and a reflective semiconductor optical amplifier, wherein the first optical circulator is interconnected and provided between one end of the two semiconductor optical amplifiers and the second switch, the second optical circulator is connected with the other end of the two semiconductor optical amplifiers, and the reflective semiconductor optical amplifier is interconnected and provided between the second optical circulator and the first switch.

4. The optical wavelength division node of claim 1 , wherein the OLT transmits and receives light sources via at least two arrayed waveguide gratings.

5. An optical wavelength division node interconnected and provided between an optical line terminal (OLT) and a plurality of optical network unit (ONU), comprising: a filter for receiving a downstream signal light source and a signal-free light source with different wavelengths transmitted by the OLT, and separately transmitting the received downstream signal light source and the signal-free light source received from the OLT; a plurality of optical circulators sequentially and individually connected to each of the plurality of ONUs, wherein the optical circulator in a first-order position receives the downstream signal light source transmitted by the filter and transmits the downstream signal light source received from the filter to the ONU in a first-order position, so as to receive a return signal transmitted by the ONU in the first-order position and pass the return signal received from the ONU in the first-order position to the optical circulator in a second-order position, until the optical circulator in a last-order position receives the return signal transmitted by the ONU in a last-order position and transmits the return signal received from the optical circulator in the last-order position; and a colorless light source module for receiving the signal-free light source transmitted by the filter and the return signal transmitted by the optical circulator in the last-order position, and using the signal-free light source to modulate the return signal received from the optical circulator in the last-order position to generate an upstream signal light source to be then transmitted back to the OLT by the filter; wherein the colorless light source module comprises at least two colorless light source transceivers, a first switch and a second switch; wherein the first switch is connected with the two colorless light source transceivers and the optical circulator in the last-order position; and wherein the second switch is connected with the two colorless light source transceivers and the filter.

6. The optical wavelength division node of claim 5 , wherein each colorless light source transceiver includes two semiconductor optical amplifiers, a first optical circulator, a second optical circulator and a reflective semiconductor optical amplifier, wherein the first optical circulator is interconnected and provided between one end of the two semiconductor optical amplifiers and the second switch, the second optical circulator is connected with the other end of the two semiconductor optical amplifiers, and the reflective semiconductor optical amplifier is interconnected and provided between the second optical circulator and the optical circulator in the last-order position.

7. The optical wavelength division node of claim 5 , wherein the OLT transmits and receives light sources with the optical wavelength division node via at least two arrayed waveguide gratings.